GESTATIONAL COVID19: MORPHOLOGICAL ALTERATIONS AND DECREASED HLA-G EXPRESSION CAUSED BY SARS-COV-2 INFECTION

Background: The evaluation of the effect of SARS-CoV-2 infection during pregnancy has raised interest. Even if virus vertical transmission is still controversial, several researches have focused on the possible distinctive markers associated with different susceptibility to SARS-CoV-2 infection during pregnancy (Greco, Sanz et al. 2023, Schiuma, Beltrami et al. 2023).
Aim: Evaluate the effect of SARS-CoV-2 infection at tissue level in gestational COVID-19
Methods: Morphological alterations were assessed in the placental / chorionic villi, chorionic plate, basal plate, and umbilical cord tissues obtained from 7 subjects with symptomatic respiratory SARS-CoV-2 infection and compared with those in 7 non-COVID control subjects. The expression of SARS-CoV-2 Nucleoprotein (NP) and Human Leukocyte Antigen-G (HLA-G) was estimated by the use of immunohistochemistry.
Results: The 57%, 42,8%, and 28,6% of placental / chorionic villi, chorionic plate, and basal plate, respectively, were found positive for NP antigen (p<0.01), while none of the umbilical cords stained for NP. Placental / chorionic villi samples showed the highest positivity for NP. The presence of NP positivity correlated with high levels of the fibrinoid component in placental / chorionic villi samples and leukocyte infiltration in basal plate. All placental / chorionic villi samples were found positive for HLA-G, independently from NP staining. All the NP positive chorionic plate and half of the NP positive basal plate samples expressed HLA-G. On the contrary, the placental / chorionic villi, chorionic plate, and basal plate of all non-COVID subjects were positive for HLA-G, with a higher H-score in comparison to pathological samples (p<0.05).
Conclusions: The presence of SARS-CoV-2 NP expression in gestational tissues correlates with morphological alterations and a decreased HLA-G expression compared to the control group. These data suggest a possible implication of SARS-CoV-2 infection in morphological and protein expression modification during pregnancy, which might impact infection susceptibility, pregnancy complications, and vertical transmission.